This Physics quiz is called 'Electricity - Static Electricity' and it has been written by teachers to help you if you are studying the subject at senior high school. Playing educational quizzes is one of the most efficienct ways to learn if you are in the 11th or 12th grade - aged 16 to 18.
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Have you ever been 'zapped' as you get out of a car or touched metal shelving in a shop with carpeting on the floor? Have you ever rubbed a balloon on your clothing and stuck it to a wall? Have you ever watched lighning during a storm? If you have, then you have experienced static electricity in action!
Static electricity is a stationary electric charge, produced by friction acting on certain electrical insulators. As you rub an insulator, such as the soles of your shoes on the carpet or the balloon on your clothing, electrons are knocked off some of the atoms and are transferred from one to the other.
Since an insulator does not allow charge to move easily through it, the charge builds up on the surface. Although the charge cannot pass through the insulator, it can move around the surface and the whole of the surface becomes charged. If you are attached to a charged material, you also will become charged, which is why, when you touch a conductor such as a car door or metal shelf, the static electricity becomes current electricity and you receive an electric shock.
It affects many things in our daily lives and can be a major issue in the manufacture of small electrical devices, which are easily damaged by static electricity. Many computer manufacturers have electrically conductive flooring to ensure that static electricity is not produced when their workers are producing microchips. Computer repairers will also usually wear an anti-static bracelet that connects to the casing of the inside of a computer. This ensures that they are always at the same electrostatic potential as the computer as they know that an accidental discharge of static electricity (they call it an ESD - electrostatic discharge) could destroy the sensitive electronics.
When static electricity is generated, one insulator becomes negatively charged and the other becomes positively charged - the one that receives the electrons is negative. Oppositely charged objects attract one-another, but any charged object can attract small uncharged objects. This is why plastic materials and things like computer screens and TV screens attract so much dust.
Static electricity can be extremely dangerous in certain conditions - the most obvious is if you are hit by lightning. In factories producing finely ground materials, like flour for example, sparks of static electricity have caused deadly explosions. As the fine particles are pumped around a factory, they rub against each other and this friction makes them statically charged. The charge spreads out on the surface of the pipes and when it builds up to the point where it can spark, if there are a lot of the fine particles in the air, they could ignite - you should know from chemistry that powdered materials burn much faster than lumps. The same applies to pumping inflammable liquids - high concentrations of vapor can be ignited by a spark. This is prevented by connecting the pipes to the ground through a conducting wire, and also by reducing the amount of dust or vapor in the air during the operation.
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